To qualify for the Raid Finder, you need to have an average item level of 372. This is totally doable, even with a freshly dinged level 85 mage clad in quest reward hodgepodge, and it's doable without a whole of time and effort expended. The aim of this guide is to take you from those leveling greens to raid-worthy purples in as little time as possible.
Your first stop on the gearing ladder is the normal Dungeon Finder. You may have already been using this as you leveled to 85, but before you can begin gearing in earnest, you have one barrier to entry, and that's the item level 329 requirement to queue for heroics. Honestly, at this point in the expansion, this section on the gearing expressway is little more than a speed bump. So hop back in there a few more times. It really shouldn't take you long to grab some nice high-level blues to fill your most lacking slots.
If you've gained any reputation with the Cataclysm factions at all while leveling (and frankly, it's tough not to), hit up their various faction vendors and purchase whatever they offer that will help you. Crafted gear can also work wonders for a new level 85 mage, so either befriend a tailor, hit up the Auction House, or learn to sew. Whatever you do, though, don't spend too much time or money getting anything pre-heroic. You'll be replacing it so quickly it's ridiculous, and your only goal here is to cobble together enough gear to get into those heroics.
The real prize in the random normals -- the only thing of any lasting value -- is justice points. With each normal 5-man run, you'll also be hauling in fair chunks of this currency, which you can now use to purchase item level 378 gear. Not only are you vastly improving your gear level average and getting yourself ready for the 4.3 5-mans, you're already getting Raid-Finder-level equipment.
As soon as you feel up to it, you should also hit up the Firelands quest lines, which begin in your faction's home city and Mt. Hyjal. Much of the epic gear you can grab there requires very little work to obtain and will greatly assist you in becoming heroic-worthy.
Your next goal involves random heroics until your item level is high enough to enter the new patch 4.3 5-man instances. The magic number here is item level 353, and it really shouldn't take long. All of the purple drops in the two troll instances are item level 353, and you'll be picking up some upgrades in even the older heroics -- but again, the main reason we're here is to pick up stacks and stacks of justice and valor points. Keep using your justice points on patch 4.2 badge gear while you save up your valor points for the occasional fat piece of item level 397 sweetness.
Valor point gear
With time put in, there are numerous slots you can fill with valor point items. A full list:
Patch 4.3 5-man heroics
Head Hood of Hidden Flesh 2,200 VPs
Chest Robes of Searing Shadow 2,200 VPs
Wrist Chronoboost Bracers 1,250 VPs
Hands Clockwinder's Immaculate Gloves 1,650 VPs
Waist Tentacular Belt 1,650 VPs (By the way, this is absolutely my new favorite adjective: tentacular. I think it should be used by sportscasters to describe athletes. "Bob, that blocked shot was just amazing. That young man is simply tentacular!" Also, I'm 99% sure that when you describe an article of clothing as "tentacular," I don't want that article of clothing anywhere near my crotch. Or maybe I do? I'm extremely confused now.)
Feet Kavan's Forsaken Treads 1,650 VPs
Back Nanoprecise Cape 1,250 VPs
Finger Seal of the Grand Architect 1,250 VPs
Neck Opal of the Secret Order 1,250 VPs
Trinket Bottled Wishes 1,650 VPs (Incidentally, this is also what I call A1 Steak Sauce.)
Wand Hungermouth Wand 700 VPs
By now, you should more than geared enough to start farming the newest 5-mans in the game for all of the item level 378 loot that drops therein. What to look for:
Well of Eternity
Hour of Twilight
It is entirely possible to obtain a level 378 piece for every slot with drops from these three instances alone, with the exception of one ring and one trinket. Those are the pieces I'd focus on filling with justice and valor points if need be, and then start saving those points for the tier sets, and fill the rest of your needs with the 5-man drops.
And on to the Raid Finder ...
Once your average gear level is high enough, read up on the fights and jump directly into the Raid Finder. Deathwing needs killing, and you're just the mage to give him what he needs. Warlocks also need killing, but I don't need to tell you that. You're a mage
Every week, Arcane Brilliance teleports you inside the wonderful world of mages and then hurls a Fireball in your face. Start out with our recent beginner's guide to being a mage, then check out our three-part State of the Mage columns on arcane, fire and frost. Don't forget to look at some of the addons your mage should probably be using.